κ-Carrageenan hydrogel nanocomposites with release behavior mediated by morphological distinct Au nanofillers

In this work we investigate the effect of spherical and rod-shaped Au nanoparticles (NPs) in the microstructure, thermomechanical and release properties of thermosensitive κ-carrageenan hydrogels. Thermal and mechanical analyses of the composites revealed that the Au NPs reinforce the structure of the hydrogel and the mechanism of gel reinforcement is discussed. The effect of the NPs on the microstructure and strength of the hydrogel had implications in the mechanism of controlled release as demonstrated by in vitro release studies using a drug model (methylene blue: MB). Noteworthy, the mechanism of MB release followed either a diffusion or polymer relaxation mechanism, depending on the morphology of the Au NPs incorporated in the hydrogel. Consequently, κ-carrageenan hydrogels containing Au NPs exhibited not only optical features modulated by the fillers morphology, but also showed a behavior as drug carriers that can be also adjusted by Au NPs characteristics.